General Theory of Bimolecular Reaction Rates in Solids and Liquids

Abstract

An argument is presented to show that the theory of kinetics of diffusion limited reactions developed previously may be generalized to a theory of bimolecular reaction rates in condensed phases. The rate at which particles arrive at a separation suitable for reaction is given by differential equations describing the random walks of the particles. The probability of reaction of particles separated by this collision diameter (i.e., near neighbors in the condensed system) is given by a steric and activation energy factor. The resulting boundary value problem is solved in detail. Explicit expressions for the reaction rates are presented. The reaction follows second‐order kinetics except that the most general rate ``constant'' is time dependent. Reaction rates are discussed in terms of the diffusion parameters and forces between the reactant particles. Physical interpretations of the rate constant are suggested. Reaction rates in liquid solvents are related to the viscosity of the solvent phase. An effective capture radius is derived for particles with long‐range forces.